1. Technical Field
The present invention relates to an installation device for an instrumentation device which inhibits transmission of vibration to the instrumentation device to be mounted to the engine frame of a stationary engine, and enables prevention of faults and malfunctions of the instrumentation device.
2. Description of the Related Art
When instrumentation devices such as a sensor and an amplifier are directly fixed to an engine frame, the vibration of the engine is transmitted to the instrumentation devices, which causes faults and malfunctions of the instrumentation devices. For this reason, when the instrumentation device is mounted to the engine frame, vibration isolating measures are required. Conventionally, there has been used, for example, a vibration isolating device as shown in FIG. 7.
FIG. 7 shows an engine frame 102 of a stationary gas engine 100. The stationary gas engine 100 is provided with four cylinder heads 104. A cylinder internal pressure sensor 108 for detecting the combustion pressure in the cylinder is mounted for each cylinder head 104. A lead wire 110 is connected between the cylinder internal pressure sensor 108 and a combustion diagnosis device 114. The combustion pressure in the cylinder is transmitted to the combustion diagnosis device 114 by the lead wire 110. The diagnosis information by the combustion diagnosis device 114 is sent to a main controller 116 for controlling the operation of the stationary gas engine 100. An amplifier 112 is inserted at the midpoint of the lead wire 110.
On a plane 106 formed at the engine frame 102, an instrumentation device installation device 120 having a vibration isolating function is disposed for every cylinder. The instrumentation device installation device 120 includes a base 122 fixed to the plane 106, four wires 124 connected at respective one ends thereof to the four corners of the base 122, and a vibration isolating stage 126 to which the other ends of the wires 124 are connected. A fixing band 128 is bonded to the top surface of the vibration isolating stage 126. The amplifier 112 is held by the fixing band 128, and is fixed to the vibration isolating stage 126.
The vibration isolating stage 126 is supported in a floating sate in the air by the bending elastic force of the wires 124. Thus, by holding the amplifier 112 in a floating sate in the air, the vibration of the engine frame 102 is prevented from being transmitted to the amplifier 112. However, unfavorably, the instrumentation device installation device 120 has a complicated structure, and requires a space for installation thereof, and is expensive.
In Patent Document 1, there is disclosed a vibration isolating mechanism in which a fuel pressure (fuel pressure detection) sensor for detecting the pressure in the high pressure fuel path is mounted to the cylinder body via a vibration isolating material in an intra-cylinder fuel injecting type engine. The vibration isolating mechanism is configured as follows: the fuel pressure sensor is not in direct contact with the cylinder body; a gap is caused between the fuel pressure sensor and the cylinder body; and the fuel pressure sensor is fixed to the cylinder body via the vibration isolating material.
Patent Document 1: Japanese Patent Application Laid-open No. 2001-65386
The vibration isolating mechanism disclosed in Patent Document 1 is configured as follows: although the fuel pressure sensor is not directly fixed to the cylinder body, its own weight of the fuel pressure sensor is imposed on the cylinder body via the vibration isolating material. Accordingly, to the fuel pressure sensor, the vibration of the cylinder body becomes more likely to be transmitted through the vibration material. This imposes a given limit on the vibration isolating effect.
The stationary engine is mounted and fixed to a stationary stand. Accordingly, the vibration of the engine frame includes mostly only the vibration transmitted from the engine. For this reason, the vibrations of the engine frame are the vibrations including limited vibration frequencies. The vibrations having different vibration frequencies do not cancel each other. Thus, the vibration including a single frequency tends to be amplified. Further, when the vibration frequencies of the fuel pressure sensor and the vibration isolating material disclosed in Patent Document 1 are within a resonance generation region with the vibration frequency of the engine, the resonance phenomenon occurs, and a large vibration is caused in the fuel pressure sensor. This may cause faults or malfunction of the fuel pressure sensor.
In view of the foregoing circumstances, the present inventors conducted a study on measures for improving the vibration isolating effect of the instrumentation device installation device set in the engine frame of the stationary engine. FIG. 8 shows a vibration isolating device for a stationary gas engine (unpublished) as the intermediate technology invented before the present inventors reach the present invention.
In FIG. 8, the vibration isolating device 130 is formed of a fixing stand 132 including flange parts 132a and 132e formed by bending a plate made of one sheet of metal or hard resin, and being in contact with the plane 106 formed at the engine frame 102, sidewall parts 132b and 132d bent at right angles to the flange parts, and vertically arranged in a direction away from the plane 106, and a fixing part 132c disposed between the sidewall parts.
The flange parts 132a and 132e are bonded to the plane 106 by bolts 136. A fixing band 138 is bonded to the top surface of the fixing part 132c, and the amplifier 112 is held by the fixing band 138, and is fixed to the fixing part 132c. A vibration isolating rubber plate 140 is interposed between the fixing band 138 and the amplifier 112. The lead wire 110 establishes connections among the cylinder internal pressure sensor 108, the amplifier 112, and a combustion diagnosis device (not shown).
In such a vibration isolating device 130, the vibration of the engine frame 102 is attenuated by the vibration isolating rubber plate 140. However, the vibration transmitted from the engine frame 102 through the fixing stand 132 to the amplifier 112 is not eliminated. For this reason, as with the vibration isolating mechanism disclosed in Patent Document 1, a given limit is imposed on the vibration isolating effect.